Concrete-arch construction.



No. 696,838. Patented Apr. I, I902.

w. c. PARMLEY.

CONCRETE ARCH CONSTRUCTION.

(Application filed June 4, 1901.)

(No Model.) 3 Sheets-Sheet l.

WITNESSES: MIME/Wok. zm Lu/ By A2121. ATT'ORNEY.

TNE uonqls PETERS c0. we re-Luna, WASHINGTON. a, c

No. 696,838. Patented A' r. I, |902..

w. c. PARMLEY.

CON CRETE ARCH CONSTRUCTION.

(Application filad June 4, 1901.)

(No Model.)

3 Sheets-Sheet 2.

' ATTORNEK rm: nunms PEYERS co, mom-urns wuummom by c.

No. 696,838. Patented Apr. I, I902.

W. C. PARMLEY.

CONCRETE ARCH CONSTRUCTION.

(Application filed June 4, 1901.) (No Model.) 3 Sheets-Sheet 3.

v WITNESSES: MjWI INVENTOR. BY 1 ATTORNEY.

NrTnn STnTns PATENT rrrcn.

\VALTER O. PARMLEY, OF CLEVELAND, OIIIO.

CONCRETE- ARCH CONSTRUCTION.

SPECIFICATION forming part of Letters Patent No. 696,838, dated April 1,1902.

Application filed June 4, 1901.

To all whom, it may concern:

Be it known that I, WALTER O. PARMLEY, a citizen of the United States,residing at Cleveland, in the county of Cuyahoga and State of Ohio, haveinvented certain new and useful Improvements in Concrete-Arch.Ooustruction; aud'I do hereby declare the following to be a full,clear, and exact description of the invention, such as will enableothers skilled in the art to which it appertains to make and use thesame.

My invention relates to improvements in the construction of arches,vaults, and sewers, &c., and in particular to such as are constructed inWhole or chiefly of concrete or cement mortar, although also applicableto such constructions When built of masonry or partly of masonry andpartly of concrete.

The object of my invention is to gain increased strength in suchconstruction and also to diminish the amount of material used, and thussecure reduced cost of construction combined with increased strength.These objects I accomplish by the method of construction and thearrangement and combination of materials hereinafter described, andillustrated in the accompanying drawings, in which-.-

Figure 1 represents in vertical section an arch strengthened by embeddedtensionstrips in the intrados and extrados of the arch, the abutments ofwhich arch may be continued into any desired structure-such, forinstance, as a complete circle or oval forming a sewer or analogoustubular structure, as shown in Fig. 2-or may end in pillars or beotherwise suitably supported, as shown in Fig. 3. Fig. 4 is a transversesection similar to Fig. 1, but shows a modified arrangement of thetension-strips, wherein a continuous strip on one side and discontinuousstrips on the other side of the arch are employed in the reversearrangement of that shown in Fig. 3. Figs. 5 and 6 represent verticalsections through cylindrical structures, such as sewers 0r sewer-pipes,exhibiting the arrangement of tension-strips in such constructions. Fig.

7 represents a partial section through the crown of the arch shown inFig. 1 or Fig. 10, the plane of section being indicated by the brokenline a: 00 in Fig. 1 and showing the relative arrangement of thetension-strips in Serial No. 63,090. (No model.)

trated in Figs. 2 and at. Fig. 10 represents,

diagrammatically, the arrangement of tension-strips placed alternatelyin intrados andeXtrados to meet all possible conditions of load orstrain. Fig. 11 represents the arrangement of the tension-bars in suchan arch as shown in Fig. 2 or 10 when the point of loading and thestrains due to it are known. Fig. 12 represents the combinations oftension-bars in a similar structure in a case Where continuous barspassing through all the tensional regions are alternated with bars inthe intrados in a single tensional region only. Fig. 13 represents asewer or analogous arched structure subjected to vertical load only andhaving the alternating bars passing through tensional regions in bothintrados and extrados, and its upper part shows the arrangement of thebarsin a segmental arch whose abutments areindicated in dotted lines.

In all the figures, A indicates bars in the intrados. trados of thearch.

In the construction of concrete arches, &c., strengthened by metallicembedded strips the important consideration is to obtain the maximumstrength of construction to resist compressive or crushing strains withthe smallest amount of material. I am aware that it has before beenproposed to strengthen concrete arches by metallic strips, bars, orsimilar materials embedded in or near the intrados or extra-dos of thearch; but in such cases the arrangement of the embedded bars has notbeen such as to secure the greatest strength for the amount of materialused in the arch. In an arch such, for instance, as that shown in Fig. 3or i a weight or crushing force applied upon the crown of the arch atthe point indicated by m produces at that point a compression of thematerials forming the eX'trados of the arch and correspondingly inducesa tensile strain upon the materials forming the intrados of the arch atthe point marked 0. To resist this tensile strain tending to separatethe materials forming the intrados of the arch at the point marked 0, Ilocate in the B indicates bars located in the exmaterial at that pointbyembedding therein as the constructionproceeds metal bars, rods, strips,or plates, which bars, 850., may be plain or corrugated, angled, orformed of any desired shape, and which by the tensile strength of themetal strongly reinforce the arch and enable it to withstand loads andstrains tending to exert such tensile strain upon the intrados. The mosteconomical use of materials to secure a given strength is obtained byplacing the embedded tension-strips so as to pass through the points of.tension and so far beyond the same as to secure firm anchoragein theparts subject to compression and generally relying upon the concretechiefly or wholly to sustain the compressive strains. In order toaccomplish this end, it is necessary to know approximately the locationof such points of tension and compression in the proposed structure andto adjust the embedded strips or bars in such relation to the entiremass of the arch as will effect/the above object. To do this of coursenecessitates a knowledge of the strains to which the structure whencompleted will be subjected, and where in any given structure thedirection of greatest pressure or strain which it will have to resist isuncertain the preferable arrangement of the embedded strips or bars willbe such as to meet all the emergencies to which the structure may besubjected, and in any such case it will be desirable to provide forresistance to tensile strains which maybe exerted in different 10-cations. In an arch the tensional strain induced at o in the intrados byload applied on the crown of the arch at m in the transmission of theload strains to the abutments is transmitted to the extrados at thehaunch, as at 0, and again to the intrados at or near thespringing-line, as at 0 and the compression strains in like mannersuffer an opposite reversal and appear at m m An embedded bar, rod, orstrip extends its strengthening effect upon the concrete throughout anannular area surrounding such rod or bar. Hence when embedded near thesurface of the concrete mass its effective area of strengthening effectis substantially semicircular and extends to a distance from such roddepending in great measure upon the cross-section area of the rod orbar. Thus when bars are embedded in an arch vertically above each otherthe areas of effective strengthening due to the two bars are separatedby a lateral wedge of material on each side of a pair of bars to whichsuch effect does notextend. Tosecurethenecessarystrengthening effect ina broad arch with bars so disposed requires, therefore, the placing ofthe pairs of bars near together, thus making the cost of the structurelarge. In contradistinction to this I prefer to place the bars in suchconstructions as require the use of tension bars in both intrados andextrados in such a manner that those in the intrados alternate invertical disposition with those in the exin pairs one vertically overthe other. In this manner the tension on the arch is: effectivelyresisted by the metal bars whether the force or pressure tending tocrush thearch is greater in the vertical or horizontal direction, and bythe alternate arrangement of the tension-bars each bar becomes thestrengthening nucleus of the greatest mass of surrounding concrete, andthus affords the best means of transferring the tensile strains in themetal bars through the compressive strength of the concrete to theabutments or to the anchorage.

Another disposition of the tension-bars in cases where the load orstrains to be supported is known is shown in Figs. 2, 5, S, &c., inwhich a-single bar, rod, or plate is so disposed as to pass through allthe point of tension in an arch subjected to load, producing verticalpressure, and thus passing alternately near the intrados and eXtradosand through or near the neutral points between the areas of compressionand tension. Each bar th us performs all the useful functions of twobars one vertically above the other. The disposition ofthe tension baror strip in a substantially circular structure-such, for instance, as asewer or pipe-is shown in Fig. 5, which represents the position of therod or bar when the load or crushing strain is applied from above. Incase the strain or crushing force were to be applied laterally thedisposition of the tensionbar would be such as would be represented byFig. 5 if it were rotated ninety degrees, the tension-bar then being atthe top of the extrados and at the inner part of the sides. Obviously byalternating the tension-bars which thus pass through the tension-pointsof both intrados and eXtrados in the manner indicated in Figs. 7, 10,and 13 all the benefits of that arrangement and those due to thepeculiar disposition of the bars with regard to the tensional regionsare secured in the single structure.

The benefits of the construction above described and illustrated inFigs. 2, 8, 10, and 13 may be obtained in great degree by locating atension-bar at the tensional regions only in the intrados or extrados,extending so far beyond each such region as to afford a sufficientlyfirm anchorage in the concrete and to place a continuous bar extendingthrough the opposite side of the arch, as shown in Figs. 3, 4, 6, and 9.In such construction the bars in opposite regions-that is, in intradosand extradosmay be placed in the same or different vertical planes, aspreferred.

Figs. 4, 9, 850;, show the metal bars as arranged to sustain the tensionin continuous or groined arches. The tension is a maxiportions. oralternately with the continuous bars mum at the points marked 0 0. Inthe case of groined arches the tension-bars may pass along the line ofthe groin or transversely with the axes of the arches. In certain casesit is desirable to place one line of continuous metal bats along theintrados and place discontinuous bars along the extrados at those pointsonly where tension occurs, allowing said bars to extend far enough intothe concrete on either side to form sufficient anchorage. Thisarrangement is shown in Figsu3 and 6, where a continuous bar is shown atA and discontinuous bars at B B. In other cases this order might need tobe reversed in the manner-shown in Figs. 4 and 9.

Other cases occur in which by disposing the bars as shown in Fig. 2aportion of the intrados on either side of the crown of the arch may notbe sufficiently supported without placing the bars nearer together thanis required for the adequate support of the other In such cases byintroducing near shorter tension-bars in the intrados, as shown in Fig.12, extending along the intrados and sufficiently on either side of theregion of maximum tension to afford proper anchorage the requiredstrength is obtained without usingmore than the minimum amount ofmaterial. i

In still other cases where it is desirable to retain the disposition ofbars shownin Fig. 2 it may be desirable in view of the uncertainty whichmay exist as to the pressure and the support which the arch will receiveat the haunch, owing to change of conditions-such as unequal settling oftheground, &c.to supplement the bars shown in Fig.2 with bars passingthrough the intrados at the crownand then passing gradually through thearch, as shown in Fig.5, and along the extrados in the regions oftension near the springingline. Such an arrangement is shown in Fig. 13.Another modification may be effected by combining in alternatearrangement, as shown in Fig. 7, the bars A of Figs. 1, 3, and 6 withthe bars shown in Fig. 5, resulting in the arrangement shown in Fig.

11 or the upper part of Fig. 13. These forms are chiefly useful inembedded arches or v arches of low rise.

In the claims I use the word bar as a generic term, intending thereby toinclude rods,

plates, Webs, cabled or built-u p bars, or metal shapes or any kindanalogous to bars, strips, or rods.

hat I claim as my invention is- 1. A concrete arch having embeddedtherein metal bars which extend continuously throughall the regions oftension in intrados or extrados of the arch, and otherbars which extendthrough part only of theregious of tension in either intrados orextrados, substantially as described.

2. A concrete arch having embedded there in metal bars which extendcontinuously through all the regions of tension in intrados or extradosof the arch, and other bars alter:

nating therewith, which extend through part only of the regi'onsoftension in eitherintrados or extrados, substantially as described.

3. A concrete arch having metal bars embedded therein,both in intradosand extrados, at the regions of tension and extending continuouslythrough the regions of tension and sufficiently into the ab utments toobtain a se-' cure anchorage, the bars in the extrados being oppositethe spaces between'thosein the intrados.

4. A concrete arch having embedded therein metal bars which passcontinuously through all the regions of tension in bothintrados andextrados and other bars extending through part of the tensional regionsonly and far enough beyond to give secure anchorage.

5. A concretearch having embedded therein metal bars which passcontinuously through the regions of tensionin both intrados andext-rados and'other bars alternating therewith and extending throughpart only of the tensional regions and far enough beyond to give secureanchorage.

6. A concrete arch having embeddedtheie in metal bars which passcontinuously through the regions of tension in both intrados andextrados and other bars which extend through a single tensional regionand far enough beyond to give secure anchorage, the

bars of one set being opposite the interspac'es between the-bars of theotherset.

Kid

In testimony whereof I hereto affix my signature in presence of twowitnesses.

' WALTER O. PARMLEY'.

Witnesses:

J. F. I-IERRioK, MYRON B. VoRoE.

